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Technical, Economic, and Greenhouse Gas Reduction Potential of Combined Ethanol Fermentation and Biofuel Gasification-Synthesis at Sulphite Pulping Mills
journal contribution
posted on 2016-08-12, 00:00 authored by Abdul
M. Petersen, Asfaw G. Daful, Johann F. GörgensThe integrated production of second
generation biofuel at a sulphite
mill, by ethanol fermentation of spent sulphite liquor (SSL), can
be expanded by gasification-synthesis to produce synthetic fuels from
bark residues available onsite. The potential contributions of such
synthetic fuel production to economic and environmental performance
of the integrated facility, in comparison to ethanol production that
is accompanied by heat and power generation from bark, were determined.
Thus, bark is used either for (i) direct heat and power generation
via direct combustion in a high pressure boiler or a biomass integrated
gasification and combined cycle (BIGCC) or, alternatively, for (ii)
gasification-synthesis to produce either methanol or Fischer-Tropsch
(FT) synthesis crude (syncrude). Techno-economic evaluations and calculations
of the net greenhouse gas reduction (NGGRP) potential for all process
scenarios were conducted on the basis of Aspen Plus⊙ simulations. Combining synthetic fuels production with SSL-fermentation
at sulphite pulp mills were shown to improve the liquid fuel yields
from 15 to 69 MWth on average, thus providing both acceptable
NGGRP and investment opportunities that are financially viable. The
internal rates of return (IRRs) were shown to improve from 25% for
ethanol production only to 30% when combined with FT crude synthesis
and to 32% when combined with methanol synthesis. Thus, negating disposal
costs by utilizing waste biomass for combining synthesis fuels with
ethanol production from SSL could be profitable at small scales, while
maintaining the desired environmental benefits.